Evolutionary upgrades of the UMTS (“Universal Mobile Terrestrial System”) mobile communication network standardized by the 3GPP organization are under discussion. These upgrades constitute the basis of a future fourth generation and are also called LTE, for “Long Term Evolution”. They provide in particular for an upgrade of the core network, EPC, for “Evolved Packet Core”, in which the exchanges are performed solely in packet mode. Upon its attachment to the mobile communication network, a client entity or user equipment UE establishes a connection so as to send and receive IP data packets. A communication session is thereafter established between the client entity UE and an external packet mode data network by way of an access gateway to the network. This access gateway is the entity of the mobile communication network responsible for the interface with the external data network. Control and charging mechanisms, called “Policy and Charging Control” or PCC, are in particular provided to be applied to the sessions. The 3GPP document TS 23.203 specifies the implementation of this function in the core network EPC. Various functional entities are provided for, in particular, an entity for controlling rules PCRF, for “Policy and Charging Rules Function”, an entity for applying these rules PCEF, for “Policy and Charging Enforcement Function” and an entity AF, for “Application Function”, making it possible to implement dynamic control of rules and/or of charging for a service offered to client entities. The PCEF function is implemented at the level of the access gateway, which thus comprises a PCEF entity. Provision is made for the AF entity to be able communicate with the entity for controlling rules PCRF (or an agent entity) so as to transmit dynamic-session information and to receive notifications, for example relating to the occurrence of events. However, it is possible that no entity exists for controlling rules in the communication network. Moreover, even when such an entity does exist, it is possible that it may consent to receive commands originating only from certain AF entities. This leads to a failure of implementation of the resources command function.